Single puncture bifurcation graft deployment system

ABSTRACT

The present invention relates to the endoluminal repair of abdominal aortic aneurysms at the aortic and iliac bifurcation. In particular, a deployment system and graft are disclosed for deploying the bifurcated graft within both iliac branches, as well as the aortic trunk, from a single vascular access.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.10/690,227, filed Oct. 21, 2003, now U.S. Pat. No. 7,691,135, which is acontinuation of U.S. patent application Ser. No. 09/795,993, filed Feb.28, 2001, now U.S. Pat. No. 6,663,665, which is a divisional of U.S.patent application Ser. No. 09/266,661, filed on Mar. 11, 1999, now U.S.pat. No. 6,261,316.

BACKGROUND OF THE INVENTION

The present invention relates to the endoluminal repair of abdominalaortic aneurysms at the aortic and iliac bifurcation, and moreparticularly, to a deployment system used to deploy a self-expandingprosthesis.

Endoluminal repair or exclusion of aortic aneurysms has been performedfor the past several years. The goal of endoluminal aortic aneurysmexclusion has been to correct this life threatening disease in aminimally invasive manner in order to effectuate a patient's quick andcomplete recovery. Various vascular grafts exist in the prior art thathave been used to exclude aortic aneurysms. These prior art grafts havemet varying degrees of success.

Initially, straight tube grafts were used in the infrarenal abdominalaorta to exclude the aneurysmal sac from the blood stream therebyresulting in the weakened aortic wall being protected by the graftmaterial. These straight tube grafts were at first unsupported, meaningthat they employed stents at their proximal and distal ends to anchorthe proximal and distal ends of the graft to the healthy portions of theaorta, thereby leaving a midsection of the graft or prosthesis that didnot have any internal support. Although this type of graft at firstappeared to correct the aortic aneurysm, it met with many failures. Theunsupported nature of its midsection allowed the graft to migratedistally as well as exhibit significant proximal leakage due to theenlargement of the aorta without adaptation of the graft, such asenlargement of the graft, to accommodate the change in diameter of theaorta.

Later, technical improvements in stent design led to “self-expanding”stents. In addition, later improvements produced “Nitinol” stents thathad a “memory” that was capable of expanding to a predetermined size.Coincidentally, graft designers began to develop bifurcated graftshaving limbs that extended into the iliac arteries. The development ofbifurcated grafts allowed for the treatment of more complex aneurysms.With the advent of bifurcated grafts, the need for at least a 1.0 cmneck from the distal aspect of the aneurysmal sac to the iliacbifurcation in order to treat the aneurysm with an endoluminal graft wasno longer needed. However, proximal necks of at least 0.5 to 1.0 cmdistance from the renal arteries to the most proximal aspect of theaneurysm are still generally required.

Some bifurcated grafts are of a two-piece design, in which an aorta andipsilateral iliac segment is connected with a contralateral iliac branchin situ. The two-piece designs require the insertion of a contralaterallimb through a separate access site. These types of grafts are complexto deploy and have the potential for leakage at the connection site ofthe two limbs of the graft.

One-piece bifurcated grafts are also known in the art. For example, U.S.Pat. No. 2,845,959 discloses a one-piece seamless woven textilebifurcated tube for use as an artificial artery. Yams of varyingmaterials can be used to weave the bifurcated graft including nylon andplastic yams. U.S. Pat. Nos. 3,096,560 and 3,029,9819 issued to Liebigand Starks, respectively, disclose woven one-piece bifurcated graftswhich are constructed by performing specific types of winding andweaving about a smooth bifurcated mandrel.

U.S. Pat. No. 4,497,074 describes a one-piece bifurcated graft that ismade from a preformed support in the shape of the bifurcated graft. In afirst stage, a gel enabling a surface state close to that of theliquid-air interface to be obtained at the gel-air interface isdeposited by dipping or coating the preform with a sol which is allowedto cool. A hardenable flexible material such as a silicone elastomer isapplied by dipping or spraying the material on the mold in a secondstage. Finally, after hardening of the material, the prosthesis isremoved from the mold. In U.S. Pat. No. 4,816,028 issued to Kapadia etal., there is shown a one-piece woven bifurcated vascular graft having aplurality of warp threads running in the axial direction and a pluralityof weft threads running in the transverse direction. Further, U.S. Pat.No. 5,108,424 issued to Hoffman, Jr. et al. discloses a one-piecebifurcated collagen-impregnated Dacron graft. The bifurcated graftincludes a porous synthetic vascular graft substrate formed by knittingor weaving with at Cast three applications of dispersed collagenfibrils.

The Herweck et al. U.S. Pat. No. 5,197,976, discloses a continuousone-piece bifurcated graft having plural longitudinally parallel tubestructures which are attached to one another over at least a portion oftheir longitudinal exteriors. The tube structures can be manuallyseparated to form a branched tubular structure. The prosthesis ismanufactured by paste forming and stretching and/or expanding highlycrystalline unsintered polytetrafluoroethylene (PTFE). Paste formingincludes mixing the PTFE resin with a lubricant, such as mineralspirits, and then forming the resin by extrusion into shaped articles.

Although all of the above-described one-piece bifurcated grafts haveeliminated the problems of leakage and graft failure at the suture orjuncture site associated with two piece bifurcated grafts which jointogether two separate grafts to form the bifurcated graft, problemsstill exist with these one-piece bifurcated grafts. For example, thepreviously described one-piece bifurcated grafts do not include anintegral support structure to prevent the deformation, twisting orcollapse of the graft limbs. Further, the same problems with graftmigration that existed with straight tube grafts still exist with theone-piece bifurcated grafts. Accordingly, there is a need for a stableand durable transluminally implantable bifurcated vascular graft that isstructured to prevent the migration and deformation of the graft andobstruction of the blood flow through the limbs of the bifurcated graft.

Endoluminal implantation is an increasingly accepted technique forimplanting vascular grafts. Typically, this procedure involvespercutaneously inserting a vascular graft or prosthesis by using adelivery catheter. This process eliminates the need for major surgicalintervention thereby decreasing the risks associated with vascular andarterial surgery. Various catheter delivery systems for prostheticdevices are described in the prior art.

For example, bifurcated vascular grafts have been created by combininggrafts with stents on delivery systems in order to secure the graft endsto the blood vessel thereby stabilizing the bifurcated graft. In U.S.Pat. No. 5,360,443 issued to Barone et al., a method for repairing anabdominal aortic aneurysm is described. The method comprises the stepsof (1) connecting an expandable and deformable tubular member, such as astent, to each of the tubular passageways of a bifurcated graft, (2)disposing the bifurcated graft and deformable tubular members within theaortic and iliac arteries, and (3) expanding and deforming eachdeformable tubular member with a catheter to secure each tubularpassageway of the bifurcated graft within the appropriate artery. Thisreference only discloses a catheter delivery method for deploying theaortic portion of the bifurcated graft. The same catheter is supposedlyused to also expand and secure the associated stents within the iliacarteries.

The Palmaz et al. U.S. Pat. No. 5,316,023, describes a method andapparatus for repairing an abdominal aortic aneurysm in an aorta at theiliac arteries. This method includes the steps of connecting a firsttubular graft to a first deformable and expandable tubular member,connecting a second tubular graft to a second deformable and expandabletubular member, disposing the first tubular graft and first tubularmember upon a first catheter having an inflatable portion, disposing thesecond tubular graft and second tubular member upon a second catheterhaving an inflatable portion, intraluminally delivering the first andsecond tubular grafts, tubular members and catheters to the aorta anddisposing at least a portion of each tubular graft within the abdominalaortic aneurysm, and expanding the tubular members with the inflatablecatheters to secure them and at least a portion of their associatedtubular grafts within the aorta. This patent reference employs twoseparate unconnected straight grafts that are employed within an aortato form a bifurcated graft.

Further, U.S. Pat. No. 4,617,932 issued to Komberg discloses a devicefor inserting a graft into an artery comprising a plurality of nestedtubes each having an upper and lower end. A first outer tube has a meansfor guiding and positioning an arm means at its, upper end. The armmeans is movably attached to the upper end of another tube locatedinside of the first tube and extending above the first outer tube. Thelower ends of the tubes are adaptable for fastening means and the insidetube extends below the end of the first outer tube. Delivery andplacement of a bifurcated graft is illustrated. U.S. Pat. No. 5,522,883issued to Slater et al. describes an endoprosthesis stent/graftdeployment system which includes a tubular delivery catheter, a radiallyexpandable prosthesis positioned over the catheter, a removableendoprosthesis support assembly located adjacent the catheter openingand having an arm extending through the catheter which keeps theendoprosthesis in a compressed state, and a release mechanism insertablethrough the catheter for removing the support assembly.

U.S. Pat. No. 5,104,399 issued to Lazarus also describes an artificialgraft and delivery method. The delivery system includes a capsule fortransporting the graft through the blood vessel, a tube connected to thevessel that extends exterior to the vessel for manipulation by a user,and a balloon catheter positioned within the tube. Finally, U.S. Pat.No. 5,489,295 issued to Piplani et al. discloses a bifurcated graft anda method and apparatus for deploying the bifurcated graft. The Piplaniet al. graft includes a main tubular body, first and second tubular legsjoined to the main tubular body in a bifurcation, a first expandableattachment means for anchoring the main body located adjacent theopening for the first body, and a second expandably attachment meanslocated adjacent the opening of the first tubular leg for anchoring thefirst tubular leg. The graft is intraluminally implanted using acatheter that is inserted into the aortic bifurcation through a firstiliac artery so that the first attachment means adjacent the opening ofthe main body can be anchored in the aorta and the second attachmentmeans adjacent the opening of the first tubular leg can be anchored inthe first iliac artery. The second tubular leg is deployed into thesecond iliac artery by using a pull line attached to the second tubularleg. The Piplani et al. patent also discloses a deployment deviceconsisting of a capsule catheter, a balloon catheter, and a separateexpandable spring attachment means.

None of the described methods and devices permits delivery of aone-piece bifurcated graft from a single access site. Indeed, currentprocedures require a double or triple cut-down or percutaneous access tothe left and right femoral and/or brachial arteries to insert catheters,guidewires, and guide catheters. Accordingly, not only is there a needfor an improved structurally supported self expandable one piecebifurcated graft, but there is also a need for a delivery apparatus andmethod for deploying and implanting such a bifurcated graft from asingle access site.

SUMMARY OF THE INVENTION

There is disclosed in accordance with the present invention a deploymentsystem for deploying a bifurcated prosthesis at the junction of a mainvessel and first and second branch vessels. The system comprises adelivery catheter and a bifurcated prosthesis. The delivery catheter hasan inner core connected to a tubular housing and slidably positionedwithin a middle core. The middle core has proximal and distal ends andat least the distal end of the middle core forms a tubular sheath. Themiddle core is slidably positioned within an outer sheath. Thebifurcated prosthesis in accordance with the deployment system of thepresent invention has a main body section with proximal and distal endsand first and second branch sections at the proximal end of the mainbody section. The main body section is held in a radially compressedstate within the tubular housing of the inner core. The first branchsection is held in a radially compressed state within the tubular sheathof the middle core. And the second branch section is disposed within theouter sheath in a radially compressed state.

A method is disclosed for deploying bifurcated endoluminal prosthesis atthe junction of a main vessel, such as the aorta, and first and secondbranch vessels, such as the ipsilateral and contralateral iliacarteries. A deployment system is introduced through an access site intothe first branch vessel and advanced distally (catheter direction)through at least a portion of the first branch vessel and into the mainvessel. The deployment system contains a bifurcated prosthesiscomprising a main body section and first and second branch sections. Theproximal end of the second branch section is extended outward from thedeployment system into the main vessel in the direction of the secondbranch vessel by proximally retracting an outer sheath of the deploymentsystem. The extended second branch section is positioned within thesecond branch vessel by proximally retracting the deployment system.

The first branch section of the prosthesis is expanded from a radiallycompressed state within the deployment system to a radially expandedstate within the first branch vessel by proximally retracting a middlecore of the deployment system. The main body section of the prosthesisis expanded from a radially compressed state within the deploymentsystem to a radially expanded state within the main vessel by distallyadvancing an inner core of the deployment system. The second branchsection within the second branch vessel is expanded and the deploymentsystem is retracted distally through a central lumen in the main bodyand first branch sections of the prosthesis and oat of the patient'sbody.

In one embodiment of the disclosed method, the second branch sectioncomprises a wire support formed from a memory alloy. Consequently, thesecond branch section may be expanded by heating the wire support.

Alternatively, the second branch section may comprise a self-expandablewire support, which is mechanically restrained in a radially compressedstate by a restraint. The second branch section is then expanded byremoving the restraint. The restraint may comprise any of a variety ofstructures, such as a wire woven through or around the collapsed secondbranch or a sheath around the collapsed second branch. In oneembodiment, the sheath is peelable or tearable so that it can be removedby retraction in the proximal catheter direction. The second branchsection is expanded by axially moving the wire or sheath.

Further features and advantages of the present invention will becomeapparent to those of skill in the art in view of the disclosure herein,when considered together with the attached drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic representation of the deployment system of thepresent invention positioned within the ipsilateral iliac and the aorta.

FIG. 2 is a schematic representation of the deployment system of thepresent invention positioned within the ipsilateral iliac and the aorta,showing separation of the contralateral limb from the ipsilateral limb.

FIG. 3 is a schematic representation of the deployment system of thepresent invention illustrating positioning of the ipsilateral andcontralateral limbs of the bifurcated graft within the respective iliacbranches by proximal retraction of the deployment catheter.

FIG. 4 is a schematic representation of the deployment system of thepresent invention showing deployment of the ipsilateral limb of thebifurcated graft by withdrawal of the middle core.

FIG. 5 is a schematic representation of the deployment system of thepresent invention showing a segmented configuration of the middle core.

FIG. 6 is a schematic representation of the deployment system of thepresent invention showing deployment of the main body of the bifurcatedgraft by distally advancing the inner core.

FIG. 7 is a schematic representation of the deployment system of thepresent invention illustrating deployment of the contralateral limb ofthe bifurcated graft by applying heat, in the illustrated embodiment tothe memory alloy wire cage of the contralateral limb.

FIG. 8 is a schematic representation of the deployment system of thepresent invention showing withdrawal of the deployment catheter of thepresent invention from the fully deployed graft.

FIG. 9 is a schematic representation of the fully deployed graft of thepresent invention in situ.

FIG. 10 is a schematic representation of a variation of the deploymentsystem of the present invention showing retention of a self-expandingcontralateral limb with a small diameter filament.

FIG. 11 is a schematic representation of another variation of thedeployment system of the present invention showing a contralateral limbsheath.

FIG. 12 is a schematic representation of the deployment system of FIG.11, showing deployment of the contralateral limb by proximal retractionof a deployment wire.

FIG. 13 is a schematic representation of a variation of the deploymentsystem of the present invention, showing retention of the contralaterallimb by a peel-away limb cover.

FIG. 13A is an enlarged view of a peel-away contralateral limb cover inaccordance with the present invention.

FIG. 14 is a schematic representation of the system of FIG. 13, readyfor deployment of the contralateral limb.

FIG. 15 is a representation of the system of FIG. 14, with thecontralateral limb partially deployed.

FIG. 16 is a representation as in FIG. 15, with the contralateral limbfully deployed.

FIG. 17 is a representation of the system as in FIG. 16, with theipsilateral limb deployed.

FIG. 18 is an exploded view of a bifurcated graft in accordance with thepresent invention, showing a self expandable wire cage separated from anouter polymeric sleeve.

FIG. 19 is schematic representation of the bifurcated graft inaccordance with one embodiment of the present invention, showing anexpansion spring.

FIG. 20 is plan view of a formed wire useful for rolling into amulti-segmented wire cage in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

This invention relates to a delivery catheter and graft system fordeploying a bifurcated vascular graft, which allows deployment of thegraft from a single vascular access site. A related technique using twoaccess sites is disclosed in co-pending patent application Ser. No.08/802,478 entitled Bifurcated Vascular Graft and Method and Apparatusfor Deploying Same, filed Feb. 20, 1997, the disclosure of which isincorporated in its entirety herein by reference.

Referring to FIG. 1, an embodiment of the deployment system 10 isdepicted in situ at the bifurcation of the aorta into the ipsilateraliliac 20 (in which the deployment system 10 resides) and thecontralateral iliac 26. In general, the illustrated deployment system 10employs an over-the-wire coaxial design with three inter-moving elementsand, in one embodiment, a thermal or electrical conduit as will bedescribed. The deployment system 10 is percutaneously (or surgically)inserted into a first access site such as a femoral artery puncture (notillustrated). The system 10 is advanced distally along a guidewirethrough the ipsilateral iliac 20 and into the aorta 22, until positionedas generally illustrated in FIG. 1, spanning the site of an aorticaneurysm 24.

In an embodiment intended for femoral artery access to deploy anabdominal aortic aneurysm bifurcation graft, the deployment system 10has an overall length from proximal to distal end generally within therange of from about 90 cm to about 110 cm. As used herein, the relativeterms “proximal” and “distal” shall be defined from the perspective ofthe delivery system 10. Thus, proximal is in the direction of thecontrol end of the system (not illustrated) and distal is in thedirection of the distal tip 32.

The illustrated deployment system 10 includes an inner core 30, a middlecore 40, an outer sheath 50, and a contralateral graft actuator 60. Theinner core 30 is preferably a thin-walled tube designed to track over aguidewire, such as a standard 0.035 inch guidewire. In the illustratedembodiment, the inner core 30 preferably has as small an outsidediameter as possible to minimize the overall outside diameter of thedelivery catheter, while at the same time providing sufficient columnstrength to permit distal axial advancement of the tapered tip 32 andtubular housing 33 to deploy the main trunk of the prosthesis as will bediscussed. A section of stainless steel hypotube having an insidediameter of about 0.042 inches, an outside diameter of about 0.058inches, and an overall length of about 95 cm, depending upon the lengthof the delivery catheter, has been found suitable for this purpose.

The device 10 has a soft tapered tip 32 secured to the distal end ofinner core 30. Tapered tip 32 facilitates insertion and atraumaticnavigation of the vasculature. The tapered tip 32 can be made from anyof a variety of polymeric materials well known in the medical devicearts, such as polyethylene, nylon, PTFE, and PEBAX.

The distal tapered tip 32 tapers in one embodiment from an outsidediameter of about 0.225 inches at its proximal end to an outsidediameter of about 0.070 inch at its distal end. The overall length ofthe distal tip 32 in one embodiment of the deployment system 10 is about3 inches. However, the length and rate of taper of the distal tip 32 canbe varied within the range of from about ½ inch to about 4 or 5 inches,depending upon the desired tractability and flexibility characteristics.

A tubular housing 33 extends proximally from and is attached to or is aproximal extension of the distal tip 32. The tubular housing 33 anddistal tip 32 are connected to the inner core 30, so that distaladvancement of the inner core 30 will also distally advance the tip 32and housing 33. The tubular housing 33 serves as a sheath for retainingthe compressed main body of the bifurcated graft of the presentinvention. In one embodiment, the tubular housing 33 comprises apolyolefin extrusion having a length of about 15 cm an inside diameterof about 0.210 inches and an outside diameter of about 0.225 inches.

The distal end of the tubular housing 33 is secured to the proximal endof the distal tip 32 such as by heat shrinking, thermal bonding,adhesive bonding, and/or any of a variety of other securing techniquesknown in the art. Alternatively, the tip 32 and housing 33 may beintegrally formed such as by extrusion followed by heated stretching orother technique to taper the distal end. The distal tip 32 is preferablyalso directly or indirectly connected to the inner core 30 such as by afriction fit, adhesives or thermal bonding.

The middle core 40 comprises an elongate flexible tubular body adaptedto axially slidably track over the inner core 30. In the illustratedembodiment, the middle core 40 comprises a polyethylene or PTFEextrusion having an inside diameter of about 0.180 inches and an outsidediameter of about 0.220 inches. The inner and/or outer surfaces of themiddle core 40 may be further provided with a lubricious coating such asparalene, silicone, PTFE or others well known in the art.

The middle core 40 has a tubular distal end to slidably receiveipsilateral iliac limb 72 of the graft as will be discussed (See, e.g.,FIGS. 3 and 4). The middle core 40 may be tubular throughout its length,or may comprise a pull wire or ribbon throughout a proximal portionthereof (See, e.g., FIG. 5). The tubular distal segment has an axiallength of at least about 5 cm or longer depending upon the dimensions ofthe graft.

The outer core 50 comprises an elongate, flexible tubular body, slidablypositioned over the middle core 40. Outer core 50 also entraps therestrained contralateral limb against the outside surface of middle core40 in the illustrated embodiment.

In one embodiment, the outer sheath 50 comprises extruded PTFE, havingan Outside diameter of about 0.250 inches and an inside diameter ofabout 0.230 inches. The outer sheath 50 has an axial length within therange of from about 40 inches to about 55 inches. In the loadedconfiguration illustrated in FIG. 1, the distal end 52 of the outersheath 50 is located at least about 16 cm proximally of the distal end34 of the tapered tip 32. The outer sheath 50 may be provided at itsproximal end (not shown) with a manifold, having a hemostatic valve andaccess ports, such as for the infusion of drugs or contrast media aswill be understood by those of skill in the art.

With reference to FIG. 2, as the outer sheath 50 is retractedproximally, the contralateral limb 70 separates from the middle core 40and inclines laterally due to the resilience of the wire cage in thecontralateral limb 70. Alternatively, the limbs may separate due to aninternal separation spring connected to the ipsilateral andcontralateral limbs, with the apex of the spring located at thebifurcation. See, e.g., FIG. 14) The ipsilateral limb (hidden) remainssheathed by the middle core 40. The main body of the stent graft remainssheathed by the tubular housing 33.

The self-expandable ipsilateral limb 72 of the graft is deployed withinthe ipsilateral iliac 20, as illustrated in FIG. 4, by proximallyretracting the middle core 40. In the embodiment shown in FIG. 4, themiddle core 40 comprises a thin-walled length of PTFE tubing having anoutside diameter of about 0.215 inches. The middle core 40 moves axiallywith respect to the inner core 30.

Referring to FIG. 5, a variation of the middle core 40 design consistsof a relatively short ipsilateral sheath section 44, which is neckeddown such as by heat shrinking to secure the ipsilateral sheath section44 to a longer tubular extension 46, the combination forming themodified middle core 40. As described above, the ipsilateral limb 72 ofthe graft is deployed by proximally withdrawing the tubular extension 46so that retraction of the ipsilateral sheath section 44 releases theself-expandable wire cage from its compressed state in the ipsilaterallimb 72. The length of sheath 44 is generally in the range of from about5 cm to about 9 cm. In one embodiment in which the ipsilateral limb 72has a length of about 5.5 cm, the sheath 44 has a length of about 5.5cm.

Referring to FIG. 6, the self-expanding aortic trunk portion, or mainbody 74 of the graft 76 is released from its compressed state within thetubular housing 33 by distally advancing the inner core 30. Because thetubular housing 33 and distal tip 32 are attached to the inner core 30,the distal movement of the inner core causes the housing 33 to advance,thereby permitting the main body 74 of the graft to expand to itslarger, deployed diameter.

As illustrated in FIG. 7, the contralateral limb 70 of the graft 76 maythen be expanded within the contralateral iliac 26 by activation of thecontralateral graft actuator 60. In an embodiment in which thecontralateral graft comprises a memory metal, expansion may beaccomplished by heating the contralateral limb via actuator 60. When thememory alloy support within the contralateral limb 70 reaches itstransition temperature, which may be between 40-60.degree. C. forNitinol, the compressed wire expands to its predetermined tubular shape.

In one embodiment, power from a DC power supply or RF generator istransferred to the wire support cage from the proximal end of thedeployment system, by way of an electrically conductive graft actuator60. Any of a wide variety of electrical conductors can be utilized forthe electrically-conductive graft actuator 60, including solid wire,braided filaments and others as will be understood by those of skill inthe art. In one embodiment, a solid wire having a cross section of about0.010 inches and an insulating layer comprising polyimide and having athickness of about 0.002 inches is utilized. The electrical conductormay contact the memory alloy wire of the graft via clasp, jaws, wirebending or intermeshing, a third segment, welds, or free contact. Theelectrically conductive actuator wire is preferably coated with apolymer material providing both electrical and thermal resistance. Thethickness of the coating is preferably between about 0.001 inches toabout 0.0015 inches. The polymer materials that can be used for thecoating are materials such as PTFE, polyimide and polyester. The coatingpreferably provides insulation at temperatures ranging from about20.degree. C. to about 60.degree. C. The electrical conductor is alsoretracted with the deployment system.

Referring to FIG. 8, the deployment system 10, including the distal tip32 and tubular housing 33, the inner core 30 and middle core 40, and theactuator 60, are proximally retracted through the expanded bifurcatedgraft 76. The deployment system may thereafter be proximally withdrawnfrom the patient by way of the single vascular access site, leaving onlythe fully deployed bifurcated graft 76 spanning the aortic aneurysm 24as shown in FIG. 9.

Any of a variety of structures can be utilized to restrain thecontralateral limb 70, during placement of the graft, and thereafterrelease or expand the contralateral limb 70 within the contralateraliliac. Preferably, all such restraining and release mechanisms areoperated through the single vascular access site as has been discussed.Thus, in embodiments using removable mechanical retention structuressuch as a sheath or restraining wire proximal (inferior anatomicaldirection) retraction of the restraining structure will release theipsilateral limb, whereas proximal retraction of a release wire willadvance the restraining structure in the superior anatomical directionto release the contralateral limb 70. A release wire shall mean anysuitable structure including a wire or cord.

For example, a small diameter wire (e.g. 0.010 inch diameter) or lowprofile ribbon (e.g. 0.001 inch by 0.003 inch) restraint 100 may bewrapped or woven around a self-expanding stent cage to hold it in acollapsed profile for placement within the contralateral limb 70 asillustrated in FIG. 10. The main body 74 and ipsilateral limb 72 of theprosthesis are configured and deployed in the same manner as describedpreviously. Following placement within the contralateral iliac asdescribed above, the restraint 100 can be retracted from the proximalend of the deployment system, releasing the contralateral limb andallowing it to expand. The deployment system including the restraint 100is then removed from the single access port.

Alternatively, a water soluble adhesive can be utilized to encapsulatethe compressed contralateral limb 70. Following retraction of the outersheath 50 and positioning within the contralateral iliac 26, exposure toblood causes the dissolvable restraint material to dissolve, eventuallypermitting the contralateral limb 70 to expand to its implanteddiameter. A wide variety of biomaterials which are absorbable in anaqueous environment over different time intervals are known, including avariety of compounds in the polyglycolic acid family, as will beunderstood by those of skill in the art. In this embodiment, thebioadhesive or other bioabsorbable restraint compound mast permitsufficient time for the contralateral limb 70 to be properly positionedwithin the contralateral iliac 26 before releasing the contralaterallimb 70 as will be appreciated by those of skill in the art.

In another variation of the single vessel deployment system of thepresent invention, a tubular sheath 102 is used to restrain thecontralateral limb as shown in FIGS. 11 and 12. Before or after the mainbody 74 and ipsilateral limb 72 of the graft 76 are deployed asdescribed above, the contralateral limb 70 is deployed by proximallyretracting a release wire 103. The proximal movement of the release wire103 causes the contralateral sheath 102 to advance inferiorly into thecontralateral iliac, thereby releasing the self-expandable wire cagewithin the contralateral limb as depicted in FIG. 12.

In the embodiment of FIGS. 11 and 12, the release wire 103 comprises aproximal ipsilateral segment 104 and a distal, contralateral segment106. Ipsilateral segment 104 and contralateral segment 106 are joined atan apex 108. Apex 108 may be a bend in the release wire 103, or a jointsuch as for securing two separate segments together. The release wire103, particularly in the region of the apex 108, must have sufficientstructural integrity that proximal retraction of the proximal end ofrelease wire 103 will cause movement of the contralateral segment 106 inthe inferior direction (down the contralateral iliac away from theaorta). The contralateral iliac segment 106 is secured at its distal endto the tubular sheath 102. The release wire 103 may be formed from anyof a variety of materials and dimensions as will be apparent in view ofthe disclosure herein. In one embodiment a circular cross-section, solidwire having a diameter in the range of about 0.020 inches to about 0.030inches may be used.

Following proximal retraction of the release wire 103 to deploy thecontralateral iliac segment 70, the release wire 103 is advanceddistally, thereby drawing the tubular sheath 102 in a superior directionthrough the expanded contralateral limb of the graft and towards theaorta. A medially-directed bias exerted by apex 108 urges the tubularsheath 102 in the direction of the ipsilateral iliac. Once the sheath102 is positioned at the opening to the ipsilateral iliac, the releasewire 103 may be withdrawn. Alternatively, the release wire 103 maysimply be proximally withdrawn, drawing the tubular sheath 102 throughthe contralateral graft segment 70 as will be appreciated by those ofskill in the art in view of the disclosure herein.

In a variation of this design, a wire without an apex, which is fastenedto the distal tip of the sheath 102, may be retracted, thereby pullingthe contralateral limb sheath from outside in, through and off of thecontralateral limb and out through the lumen.

In a further embodiment of the present invention, the contralateraliliac segment 70 is restrained in its insertion profile by a peelablesheath 110. The peelable sheath 110 can be removed to release thecontralateral iliac segment 70 by proximal retraction, preferably intothe catheter. The use of one embodiment of a peelable sheath forrestraining and deploying contralateral iliac segment 70 is illustratedin FIGS. 13 through 17.

Referring to FIG. 13, there is illustrated a deployment devicepositioned within an aneurysm 24 in the aorta 22 at the bifurcation ofthe ipsilateral iliac 20 and contralateral iliac 26. The main body 74 ofthe graft has already been deployed within the aorta 22 in accordancewith techniques previously disclosed. In this embodiment, as explainedbelow, the graft tube 33 constrained the main body 74 of the graft, theipsilateral limb cover 44 constrains the ipsilateral limb 72 and apeelable sheath 110 constrains the contralateral iliac segment. Asshown, in FIG. 13, the graft tube 33, the ipsilateral limb cover 44 andthe peelable sheath 110 are arranged in a Y-configuration.

Following retraction of the outer sheath 40 in a proximal direction torelease the constrained contralateral iliac segment 70 for positioningwithin the contralateral iliac 26, (as illustrated in FIG. 13), theouter sheath 40 is distally advanced to the bifurcation as illustratedin FIG. 14. At this point, the system is prepared for release of thepeelable sheath 110.

Referring to FIG. 13A, a peelable sheath 110 is disclosed for releasablyrestraining the contralateral iliac segment 70. The peelable sheath 110comprises a tubular body 112 having a proximal (superior) end 114 and adistal (inferior) end 116. The peelable sheath 110 is secured to acontralateral graft actuator 60 such as a release wire 103. The releasewire 103 in the illustrated embodiment is secured by way of a joint 120to the proximal end 114 of the peelable sheath 110, and extends throughthe middle core 40 to the proximal end of the catheter.

The proximal end 114 of sheath 110 is preferably provided with a leader128 of sheath material to facilitate positioning the joint 126 on theipsilateral limb side of the bifurcation. Preferably, the peelablesheath 110 is provided with a peel start point 130 such as a slit,perforation, V-shaped cut, or otherwise as will be apparent to those ofskill in the art in view of the disclosure herein. The peelable sheath110 may further be provided with a perforation line, crease or othertear facilitating modification extending axially there along tofacilitate predictable tearing of the material.

The peelable sheath 110 may be made from any of a variety of thin,tearable materials as will be apparent to those of skill in the art inview of the disclosure herein. Preferably, the material exhibitssufficient strength that it will restrain the self expandablecontralateral iliac segment 70 while at the same time maintaining a lowcross sectional profile and also permitting tearing to occur with aminimal amount of traction required on the release wire 103. In oneembodiment, the peelable sheath 110 comprises a PTFE tube having a wallthickness of about 0.011″, an outside diameter of about 0.196″ and alength from the peel start point 130 to the distal end 116 of about 5.0cm. The overall length from the joint 120 to the distal end 116 is about6.0 cm. Specific dimensions may be optimized for any particular deviceas will be understood in the art. Other thin wall tearable materials mayalso be used, such as PET, HDPE, or PE.

Referring to FIG. 14, the distal end of the outer sheath 40 provides afulcrum for minimizing injury to the adjacent tissue as proximaltraction is applied to the release wire 103. Proximal retraction of therelease wire 103 pulls the peelable sheath 110 in a proximal (superior)direction, around the bifurcation and down into the tubular outer sheath40. As illustrated in FIG. 15, retraction of the pull wire 103 slidesthe tubular body 112 superiorly along the contralateral iliac segment 70such that the contralateral iliac segment 70 is released from theinferior end first. Further proximal retraction of the release wire 103causes the peelable sheath 110 to tear or split thereby permittingcomplete retraction of the peelable sheath 110 from the contralateraliliac segment 70 as illustrated in FIG. 16. Following deployment of thecontralateral iliac segment 70, the middle core 40 and/or a separateipsilateral limb cover 44, where utilized, may be proximally retractedto deploy the ipsilateral limb 72.

As will be apparent in view of the disclosure herein, the release wire103 may extend through the outer core 50 or the middle core 40, througha dedicated lumen in the wall of either, or outside of the catheter asmay be desired for particular product designs.

The release wire 103 may be attached to the peelable sheath 110 ateither the proximal end 114 or the distal end 116. In the illustratedembodiment, the release wire 103 is attached to the leader 128 at joint126. Joint 126 comprises a barbed metal cylinder for grabbing the PTFE.Any of a variety of alternate structures or materials for fastening therelease wire 103 to the peelable sheath 110 may alternatively beutilized provided the joint 126 has sufficient integrity to pull thepeelable sheath 110 and permit splitting of the sheath to release thecontralateral iliac segment 170.

Although the peelable sheath 110 in the foregoing embodiment wasdisclosed as restraining the contralateral iliac limb, the peelablesheath may be used on any of the contralateral, ipsilateral, or mainbranch portions of the graft. For example, in one embodiment, the mainbody portion of the graft is restrained within the graft tube 33, andeach of the contralateral and ipsilateral iliac graft branches arerestrained by a peelable sheath. In an alternate embodiment, all threeportions of the graft are restrained by peelable sheaths. As a furtheralternative, the main graft body and the contralateral iliac limbportions of the graft are restrained by first and second peelablesheaths and the ipsilateral portion of the graft is restrained by aproximally retractable sleeve as has been disclosed previously herein.The desirability of any of the foregoing combinations will be apparentto one of ordinary skill in the art in view of the design parameters fora particular catheter built in accordance with the present invention.

Referring to FIG. 18, an embodiment of a self-expanding bifurcatedprosthesis in accordance with the present invention is shown having apolymeric sleeve 80 and a tubular wire support 90. Many of the featuresof the self-expandable graft of the present invention are disclosed inco-pending U.S. patent application Ser. No. 09/100,481 entitled “SelfExpanding Bifurcated Endovascular Prosthesis,” filed Jun. 19, 1998, andcopending U.S. patent application Ser. No. 09/210,280, entitled“Endoluminal Vascular Prosthesis,” filed Dec. 11, 1998, the disclosuresof which are incorporated in their entirety herein by reference.

The polymeric sleeve 80 may be situated concentrically outside of thetubular wire support 90. However, other embodiments may include a sleevesituated instead concentrically inside the wire support or on both ofthe inside and the outside of the wire support. Alternatively, the wiresupport may be embedded within a polymeric matrix that makes up thesleeve. Regardless of whether the sleeve is inside or outside the wiresupport, the sleeve may be attached to the wire support by any of avariety of means, including laser bonding, adhesives, clips, sutures,dipping or spraying or others, depending upon the composition of thesleeve and overall graft design.

The polymeric sleeve may be formed from any of a variety of syntheticpolymeric materials, or combinations thereof, including PTFE, PE, PET,Urethane, Dacron, nylon, polyester or woven textiles. Preferably, thesleeve material exhibits relatively low inherent elasticity, or lowelasticity out to the intended enlarged diameter of the wire cage. Thesleeve material preferably has a thin profile, such as no larger thanabout 0.002 inches to about 0.005 inches.

In one embodiment of the invention, the material of the sleeve issufficiently porous to permit in-growth of endothelial cells, therebyproviding more secure anchorage of the prosthesis and potentiallyreducing flow resistance, shear forces, and leakage of blood around theprosthesis. Porosity in polymeric sleeve materials may be estimated bymeasuring water permeability as a function of hydrostatic pressure,which will preferably range from about 3 to 6 psi.

The porosity characteristics of the polymeric sleeve may be eitherhomogeneous throughout the axial length of the prosthesis, or may varyaccording to the axial position along the prosthesis. For example, atleast a distal portion and right and left proximal portions of theprosthesis will seat against the native vessel walls, proximally anddistally of the aneurysm. In at least these proximal and distalportions, the prosthesis preferably encourages endothelial growth, or,at least, permits endothelial growth to infiltrate portions of theprosthesis in order to enhance anchoring and minimize leakage. For thecentral portion of the prosthesis, which spans the aneurysm, anchoringis less of an issue. Instead, minimizing blood flow through theprosthesis wall becomes a primary objective. Thus, in a central zone ofthe prosthesis, the polymeric sleeve may either be nonporous, orprovided with pores that minimize or prevent leakage.

A multi-zoned prosthesis may also be provided in accordance with thepresent invention by positioning a tubular sleeve on a central portionof the prosthesis, such that it spans the aneurysm to be treated, butleaving the wire support in the proximal and distal attachment zonesexposed. In this embodiment, the exposed wires are positioned in contactwith the vessel wall both proximally and distally of the aneurysm, suchthat the wire, over time, becomes embedded in cell growth on theinterior surface of the vessel wall.

In one embodiment of the prosthesis, the sleeve and/or the wire supportis stepped or tapered, having a relatively larger expanded diameter atthe proximal end compared to the distal ends. The tapered design mayallow the prosthesis to conform better to the natural decreasing distalcross section of the aorta and iliac arteries to reduce the risk ofleakage and graft migration and potentially create better flow dynamics.

Referring to FIG. 18, the tubular wire support comprises a main body 92for traversing the aorta and a first, ipsilateral iliac limb 94, and asecondary component for extending into the second, contralateral iliaclimb 96. The contralateral limb cage may be constructed from a memoryalloy wire such as Nitinol as has been discussed. The main body andipsilateral limb structures may be constructed from a non-memory alloywire.

Referring to FIG. 19, one embodiment of the prosthesis 76 is shown,wherein the limbs expand laterally away from one another due to anexpansion spring 120, comprising an apex and first and second legportions. The leg portions are connected to the wire cage 90 of both theipsilateral and contralateral limbs at connection point 122. The apex124 of the expansion spring 120 is located at the bifurcation.

With reference to FIG. 20, one embodiment of the wire structure for theprimary wire support components is shown, wherein the wire cage isformed from one or more lengths of wire into a series of straight strutsseparated by apexes into a zig-zag pattern. The contralateral wire cagemay also be constructed from one or more zig-zag wires as illustrated.When a tubular wire cage is formed by rolling the formed wire about anaxis, the connectors 98 collectively produce a generally axiallyextending backbone that adds axial strength to the prosthesis. The wiresupport is formed in a plurality of discrete segments, connectedtogether and oriented about a common axis. A connector wire 98 connectsadjacent segments together. Opposing wire apexes of adjacent segmentscan be connected in any of a variety of ways including circumferentiallyextending sutures, solder joints, wire loops and any of a variety ofinterlocking relationships, such as those disclosed in copending U.S.patent application Ser. No. 09/210,280, filed Dec. 11, 1998, entitled“Endoluminal Vascular Prosthesis”, the disclosure of which isincorporated in its entirety herein by reference. The contralateral limbcage may be joined to the main body and ipsilateral limb component bysimilar sutures, solder joints, wire loops and/or interlockingrelationships.

The segmented configuration of the tubular wire supports facilitates agreat deal of flexibility. Each segment, though joined to adjacentsegments, may be independently engineered to yield desired parameters.Each segment may range in axial length from about 0.3 to about 5 cm.Generally, the shorter their length the greater the radial strength. Theprimary component of an endoluminal prosthesis may include from about 2to about 50 segments, preferably from about 8 to about 16 segments.

In general, each of the components of the tubular wire support can bevaried considerably in diameter, length, and expansion coefficient,depending upon the intended application. For implantation within atypical adult, the aorta trunk portion will have a length within therange of from about 5 cm to about 12 cm, and, typically within the rangeof from about 9 cm to about 10 cm. The unconstrained outside expandeddiameter this portion will typically be within the range of from about20 mm to about 40 mm. The unconstrained expanded outside diameter ofthis portion can be constant or substantially constant throughout itslength, or can be tapered from a relatively larger diameter at theproximal end to a relatively smaller diameter at the bifurcation. Ingeneral, the diameter of the distal end will be on the order of no morethan about 95% and, preferably, no more than about 85% of the diameterof the proximal end of the aortic trunk portion.

Different zones of the prosthesis can be provided with differingexpanded diameters. Further, the different zones can be provided with adifferent radial expansion force, such as ranging from about 2 lbs. toabout 8 lbs. In one embodiment, the proximal zone is provided with agreater radial force than the central zone and/or distal zone. A greaterradial force can be provided in any of a variety of manners, such asthrough the use of additional wire bends and wall sections.Alternatively, additional spring force can be achieved through the useof a heavier gauge wire. Increased radial force and expansion diameterin the proximal and distal regions relative to a central region can beachieved by tightening a circumferential suture such that the centralregion is retained under compression even in the expanded configuration.By omitting a circumferential suture at the proximal end and/or distalends of the prosthesis, the proximal end and distal ends will flairradially outwardly to a fully expanded configuration.

The wire for the main body and ipsilateral limb cages may be made fromany of a variety of different alloys, such as elgiloy or MP35N, or otheralloys which include nickel, titanium, tantalum, or stainless steel,high Co—Cr alloys or other temperature sensitive materials. For example,an alloy comprising Ni 15%, Co 40%, Cr 20%, Mo 7% and balance Fe may beused. The tensile strength of suitable wire is generally above about 300K psi and often between about 300 and about 340 K psi for manyembodiments. In one embodiment, a Chromium-Nickel-Molybdenum alloy suchas that marketed under the name Conichrom (Fort Wayne Metals, Indiana)has a tensile strength ranging from 300 to 320 K psi, elongation of3.5-4.0% and breaking load at approximately 80 lbs. to 70 lbs. Asmentioned above, at least the contralateral limb cage may be constructedfrom a memory alloy such as Nitinol, which will remain in a smallprofile until heated to the memory alloy's transition temperature, atwhich point the contralateral limb cage expands to a predisposed shape.In any case, both the memory and non-memory alloy wires may be treatedwith a plasma coating and be provided with or without additionalcoatings such as PTFE, Teflon, Perlyne, drugs, and others as will beunderstood by those of skill in the art.

In addition to segment length and bend configuration, anotherdeterminant of radial strength is wire gauge. The radial strength,measured at 50% of the collapsed profile, preferably ranges from about 2lb. to 8 lb., and generally from about 4 lb. to about 5 lb. or more.Preferred wire diameters in accordance with the present invention rangefrom about 0.004 inches to about 0.020 inches. More preferably, the wirediameters range from about 0.006 inches to about 0.018 inches. Ingeneral, the greater the wire diameter, the greater the radial strengthfor a given wire layout. Thus, the wire gauge can be varied dependingupon the application of the finished graft, in combination with/orseparate from variation in other design parameters.

A wire diameter of approximately 0.018 inches may be useful in the aortatrunk portion of a graft, while a smaller diameter such as 0.006 inchesmight be useful for the iliac limb segment.

In one embodiment of the present invention, the wire diameter is taperedthroughout from the proximal to distal ends. Alternatively, the wirediameter may be tapered incremental or stepped down, or stepped up,depending on the radial strength requirements of each particularclinical application. In general, in the tapered or stepped wireembodiments, the diameter of the wire in the iliac branches is no morethan about 80%, preferably no more than about 50%, and optimally no morethan about 35% of the diameter of the wire in the aortic trunk. Thispermits increased flexibility of the graft in the region of the iliacbranches, which has been determined by the present inventors to beclinically desirable.

Additional details of the wire cage layout and construction can be foundin co-pending U.S. patent application Ser. No. 09/034,689 entitled“Endoluminal Vascular Prosthesis,” filed Mar. 4, 1998, the disclosure ofwhich is incorporated in its entirety herein by reference.

The collapsed prosthesis in accordance with the present invention has adiameter in the range of about 2 to about 10 mm. Preferably, the maximumdiameter of the collapsed prosthesis is in the range of about 3 to 6 mm(12 to 18 French). More particularly, the delivery catheter includingthe prosthesis will be 19 F, 16 F, 14 F, or smaller. After deployment,the expanded endoluminal vascular prosthesis radially self-expands to adiameter anywhere in the range of from about 20 to about 40 mm,corresponding to expansion ratios of about 1:2 to 1:20. In a preferredembodiment, the expansion ratios range from about 1:4 to 1:8, morepreferably from about 1:4 to 1:6.

While a number of variations of the invention have been described indetail, other modifications and methods of use will be readily apparentto those of skill in the art. Accordingly, it should be understood thatvarious applications, modifications and substitutions may be made ofequivalents without departing from the spirit of the invention or thescope of the claims.

1. A graft deployment system, comprising: an elongate, flexible catheterbody, having a proximal end and a distal end; a main vessel graftrestraint for restraining a main vessel portion of a graft; a firstbranch vessel graft restraint for restraining a first branch vesselportion of the graft; and a second branch vessel graft restraint forrestraining a second branch vessel portion of the graft; wherein: themain vessel graft restraint, the first branch vessel graft restraint,and the second branch vessel restraint are arranged in a Y-configurationthat is advanced through a first puncture site in a patient'svasculature; and the deployment system is configured such that the mainvessel graft restraint, the first branch vessel graft restraint, and thesecond branch vessel graft restraint are connected to a portion of saidgraft deployment system to be withdrawn with the graft deployment systemthrough the first puncture site after deployment of the main vesselgraft portion of the graft, the first branch vessel portion of thegraft, and the second branch vessel portion of the graft.
 2. Thedeployment system of claim 1, wherein the second vessel graft restraintcomprises a water-soluble bioadhesive.
 3. The deployment system of claim2, wherein the water-soluble bioadhesive comprises compounds in thepolyglycolic acid family.
 4. The deployment system of claim 1, whereinthe main vessel graft restraint is perforated along at least a portionof a length thereof.
 5. The deployment system of claim 1, wherein atleast one of the main vessel graft restraint, the first branch vesselgraft restraint, and the second branch vessel graft restraint isperforated along at least a portion of a length thereof.
 6. Thedeployment system of claim 1, wherein said graft is a bifurcated graft.7. The deployment system of claim 1, further comprising an outer sheath,an inner core that is axially moveable with respect to the outer sheath,and a distal tip coupled to the inner core.
 8. The deployment system ofclaim 1, wherein the first and second branch vessel graft restraints areseparate restraints.
 9. The deployment system of claim 1, wherein thegraft comprises a self-expanding support structure positioned inside themain vessel portion of the graft, the first branch vessel portion of thegraft, and the second branch vessel portion of the graft.
 10. Thedeployment system of claim 1, wherein a length of the first branchvessel portion of the graft is approximately the same as a length of thesecond branch vessel portion of the graft.
 11. The deployment system ofclaim 1, wherein the deployment system is configured such that the firstbranch vessel graft restraint is configured to be removed from the firstbranch vessel portion of the graft after the first branch vessel portionof the graft is inserted into the first branch vessel, and the secondbranch vessel graft restraint is configured to be removed from thesecond branch vessel portion of the graft after the second branch vesselportion of the graft is inserted into the second branch vessel.
 12. Thedeployment system of claim 1, wherein the first branch vessel graftrestraint covers only the first branch vessel portion of the graft andthe second branch vessel graft restraint restrains only the secondbranch vessel portion of the graft.
 13. The deployment system of claim1, wherein the first puncture site is in a first branch vessel, thefirst branch vessel portion of the graft is deployable in the firstbranch vessel by removal of the first branch vessel graft restraint, andthe second branch vessel portion of the graft is deployable in a secondbranch vessel by removal of the second branch vessel graft restraint,which restrains only the second branch vessel portion of the graft. 14.The deployment system of claim 1, wherein a portion of the graftdeployment system containing the graft is configured to be introducedthrough the first puncture site and, after deployment of the main vesselgraft portion of the graft, the first branch vessel portion of thegraft, and the second branch vessel portion of the graft have beendeployed, the portion of the graft deployment system that had containedthe graft prior to deployment is withdrawn from the first puncture site.15. A graft deployment system, comprising: an elongate, flexiblecatheter body, having a proximal end and a distal end and comprising anouter sheath and an inner core that is axially moveable with respect tothe outer sheath and a distal tip positioned adjacent the distal end ofthe catheter body; a graft having a main vessel portion, a first branchvessel portion, and a second branch vessel portion; and a restraintsystem configured to restrain the main vessel portion, the first branchvessel portion, and the second branch vessel portion; wherein: thedeployment system is configured to be inserted through a first puncturesite in a first branch vessel of a patient's vasculature; the restraintsystem comprises a second branch vessel restraint configured to restrainonly the second branch vessel portion that is positionable in the secondbranch vessel; and the restraint system is configured to be completelywithdrawn through the first puncture site in the first branch vesselafter deployment of the main vessel portion, the first branch vesselportion, and the second branch vessel portion.
 16. The deployment systemof claim 15, wherein the graft is a bifurcated graft.
 17. The deploymentsystem of claim 15, wherein the restraint system comprises at least onepeelable sheath.
 18. The deployment system of claim 15, wherein therestraint system comprises at least one perforated sheath.
 19. Thedeployment system of claim 15, comprising a peelable tubular sheath torestrain the main vessel portion of the graft.
 20. The deployment systemof claim 15, comprising a first peelable tubular sheath to restrain themain vessel portion of the graft and a second peelable tubular sheath torestrain at least the second branch vessel portion of the graft.
 21. Thedeployment system of claim 15, wherein at least the portion of therestraint system restraining the main vessel portion and the secondbranch vessel portion of the graft is perforated.
 22. The deploymentsystem of claim 15, wherein at least a portion of the restraint systemis coupled to the inner core.
 23. The deployment system of claim 15,wherein the distal tip is coupled to the inner core.